Noted

Life expectancy doesn't tell you how LONG people live https://t.co/JXBUHMy2A2

— NassimNicholasTaleb (@nntaleb) November 4, 2015

Many people keep boasting that we tend to live longer than our ancestors using the misinterpreted measure of life expectancy. 

Life expectancy doesn't tell you how LONG people live. It mostly tells you how many children fail to survive. So reducing childhood mortality when it is high extends life expectancy much more than efforts aiming at making people live longer. 

For instance bringing childhood mortality down from 30% to what we have today, close to 0, extends life expectancy by about 25 years --which is the bulk of the gains since the middle ages. 

If you want to really measure how long people live, use the expectancy at 40. For those into these things, this is the perfect illustration of the beautiful concept of ergodicity.